Traditional cameras work by exposing a piece of film (celluloid covered with a light-sensitive emulsion, such as silver nitrate) to light for a fixed amount of time. The film reacts to the light that passes through the camera's lens, "capturing" reflected images.
The biggest advantage of traditional photography is that, depending on the equipment and conditions, a photograph can have almost infinite resolution. That is, its quality is not limited by the finite number of "dots" that comprise the image.
Traditional photography also has some drawbacks. Film must be processed before the results can be seen. Great care must be taken to preserve the negative image produced on the film. It can be extremely difficult to modify a film-based photograph, using traditional processing methods. Finally, film processing and printing can be a slow, expensive process.
And the New Way
Instead of using only a lens to capture light, most digital cameras use a charge-coupled device (CCD) to convert light into a digital image. CCDs are commonly used on scanners and video cameras as well as digital cameras.
After capturing an image, a digital camera stores it in a special type of memory or on a magnetic disk. Manufacturers have developed a variety of storage technologies. Some cameras use a standard 3.5-inch floppy disk for storage. Other cameras use PC Cards or special "memory sticks" to hold photos; these devices use flash memory to store data even when the camera is turned off.
Digital cameras can store photos in a variety of formats, which may require different amounts of storage and provide varying resolutions. Most digital cameras can store images in high-resolution JPEG or TIFF formats, but these formats consume a great deal of storage space.
The biggest advantage of digital photography is convenience. Many cameras provide LCD screens so you can review a picture right after taking it. This lets you decide whether you want to keep or delete the picture. Instead of taking film to a developing lab, you can copy the images to a PC and print them out.
Printing is both the biggest blessing and biggest curse of digital photography. Even though digital cameras store pictures at very high resolutions (millions of pixels per image), the printed image's quality is restricted to the printer's quality. So, if you use a color ink jet printer with a resolution of 300 x 600 dpi, that's as good as your images will look. For best results when printing digital photographs, use premium-quality photo printing paper, which is available at any office supply store.
You can use color laser printers for higher-resolution printing, but they are very expensive. A less expensive option is the snapshot printer, which offers near-photographic resolution, but snapshot printers are slow and most print only small formats.
Even so, digital cameras are a boon to many people. You can use digital photos in Web pages and documents. Using PhotoCD or a CD-R device, you can store hundreds of photos on a single disk. And, in spite of their limited resolution, home-printed photos are faster and cheaper than professionally printed photos from film.